Wear behavior of laser clad 316L+WC composite coatings

Austenitic stainless steels (e.g. SS316L) are widely used due to their corrosion resistance and good toughness. However, their applications are still limited by their relatively poor tribological properties. A composite coating in zones subjected to contact loading appears as an interesting solution, combining the matrix material with hard reinforcements. Among the possible reinforcements, WC is a popular candidate due to its hardness and its theoretical high melting temperature of 2600°C.
Laser cladding (LC) is particularly well-suited for the manufacturing of composite coatings, allowing for a large variability in raw materials. In LC, a stream of a powder, or a mixture of different powders, is fed into a focused laser beam while being scanned across a substrate, thus leaving behind a coating or object.
This work considers a metal matrix composite composed by 316L stainless steel and reinforcements of tungsten carbides (WC) particles (10 and 20 in vol.%). During the fabrication of the coatings, the original WC particles dissolve partially in the melted SS316L matrix. The final microstructures are composed by the surviving parent WC reinforcements surrounded by a matrix that is itself reinforced as a result of the reactions with the original WC particles. The wear behaviour of those new microstructures are investigated by means of pin-on-disc tribometer tests and compared with SS316L reference samples also produced by LC. Profilometer measurements and SEM observations are carried out post-mortem on the worn samples to help elucidate the complex sequence of wear mechanisms at play during the tribometer tests.